Panton-Valentine Leukocidin–Positive CC398 MRSA in Urban Clinical Settings, the Netherlands

We report detection of Panton-Valentine leukocidin–positive clonal complex 398 human-origin methicillin-resistant Staphylococcus aureus L2 in the Netherlands. This hypervirulent lineage originated in the Asia-Pacific Region and could become community-acquired in Europe after recurrent travel-related introductions. Genomic surveillance enables early detection to guide control measures and help limit spread of pathogens in urban settings.

We report 3 patients in the Netherlands with infections caused by hypervirulent PVL-positive CC398 HO-MRSA L2 strains. The cases were detected as part of a CC398 MRSA surveillance study in a single urban area during 2014-2018 (7). One patient had furunculosis skin infection, 1 had a plantar abscess soft-tissue infection, and 1 patient with cystic fibrosis had recurrent bronchitis. One patient had a recent travel history to Vietnam in the Asia-Pacific Region, but none had livestock contact. Phenotypic susceptibility testing of patient samples confirmed methicillin resistance and the MRSA strains were sent to reference laboratories as part of routine molecular surveillance in the Netherlands. Wholegenome sequencing (WGS) and core genome multilocus sequence typing (cgMLST) were performed as part of the CC398 MRSA surveillance study. Detection of 3 PVL-positive CC398 isolates prompted comparative genomic analysis of single-nucleotide polymorphisms (SNPs) outside the scope of the surveillance study. The medical ethical committee of the Leiden University Medical Center approved the study protocol and waived the need for patient consent (approval no. G18.021/SH/sh).
MLST showed sequence types (STs) belonging to CC398, including ST1232 (n = 2), a single-locus variant of ST398, and ST4081 (n = 1), a double-locus variant of ST398. WGS and comparative genomic analysis of SNPs confirmed that all isolates were part of the same L2 lineage within the II-GOI clade ( Figure) (1-6). We performed cgMLST on 1,861 genes, and results showed each patient had a different complex type (CT), CT6700, CT6814, and CT7459, thus ruling out direct transmission events between the patients.
In conclusion, clinicians should be aware of recurrent introductions and evolutionary changes of hypervirulent PVL-positive CC398 HO-MRSA L2 strains in the Netherlands. All 3 patients carrying the detected strains manifested relevant infections, but clinical outcomes were not evaluated in the surveillance study. Additional studies could investigate travel-related transmission routes, disease burden, and clinical outcomes

RESEARCH LETTERS
We report detection of Panton-Valentine leukocidin-positive clonal complex 398 human-origin methicillin-resistant Staphylococcus aureus L2 in the Netherlands. This hypervirulent lineage originated in the Asia-Pacific Region and could become community-acquired in Europe after recurrent travel-related introductions. Genomic surveillance enables early detection to guide control measures and help limit the spread of pathogens in urban settings. of patients. In addition, future studies could determine if PVL-positive CC398 HO-MRSA strains are becoming established as community-acquired pathogens in urban settings in Europe. We recommend active WGS surveillance for early clinical recognition of PVLpositive CC398 MRSA, which can guide prevention and control measures and limit inter human transmission and severe clinical outcomes. Maximum-parsimony tree of Panton-Valentine leukocidin-positive CC398 MRSA detected in urban clinical settings, the Netherlands. Bold text indicates 3 HO-MRSA strains detected in this study, which we deposited in GenBank (accession nos. SRR21673410 for L2-P01, SRR21624599 for L2-P02, and SRR21673965 for L2-P03); those strains were compared with 27 CC398 Staphylococcus aureus strains from GenBank. The tree was constructed by using GenBank accession no. AM990992.1 as a reference strain, and then rooted and grouped into clades, as previously described (1)

About the Author
Dr. Gooskens is a clinical microbiologist at the Department of Medical Microbiology, Leiden University Medical Center, Leiden, the Netherlands. His current research interests focus on clinical molecular diagnostics and antimicrobial resistance of CC398 Staphylococcus aureus.